Disc drives are digital data storage devices that store and retrieve large amounts of user data in a fast and efficient manner. Data are magnetically recorded on the surfaces of one or more data storage discs affixed to a spindle motor for rotation at a constant high speed.
An array of vertically aligned data transducing heads are controllably positioned by an actuator to read data from and write data to tracks defined on the disc recording surfaces. An actuator motor rotates the actuator to move the heads across the disc surfaces. The heads are suspended from gimbal assemblies extending from arms of the rotary actuator assembly and include aerodynamic features that enable the heads to fly upon a fluid air bearing established by currents set in motion by the rotation of the discs. When the disc drive is deactivated, a shutdown operation is commenced wherein the heads are moved to a safe parking position before the discs come to a stop.
It is a continuing trend in the disc drive industry to provide disc drives with ever increasing data storage capacities using the same or smaller form factor (i.e., outside dimensions) for the drives. As a result, successive generations of drives are often provided with discs that are closer together, reducing disc to actuator arm clearances. At the same time, disc drives are being utilized in harsher environments, such as portable computers, requiring increases in the robustness of the drives to withstand ever greater external vibration and shock input levels. For example, a typical disc drive might be required to withstand up to 200 g mechanical shock.
Such mechanical shocks can cause significant deflection of the discs, leading to catastrophic damage to the disc media and heads. More particularly, disc to actuator arm contact can induce a shock wave large enough for referral to the gimbal assemblies and heads, causing the heads to flex off the landing zones as a result of the relatively flexible gimbal assemblies. The heads can thus achieve significant velocities in accelerating from and back toward the discs. When such velocities are sufficiently severe, damage can occur to the heads and the disc surfaces as the heads strike landing zones. Moreover, the corner of a tilted head can strike the disc surface, increasing probability of damage to the head or to the disc.
While prior art disc snubbers have limited deflection of disc drive discs, it has been observed that localized snubbers can be displaced upon application of a mechanical shock. In a relatively small computer such as a laptop, where space is limited, the added cost of assembly and installation of extra pieces can defeat the purpose of a low cost, space efficient computer.
Accordingly, there is a need for an improved approach to minimizing damage to a disc drive as a result of non-operational shock by limiting the ability of the discs to contact the arms and heads of an actuator of the disc drive.